Electrical receptacles having hinged cover plates are commonly used in applications where it is desirable to protect the components contained therein against corrosion or damaging environments. Generally, the cover plate is designed such that it automatically closes to seal off the exposed end of the receptacle when it is not being used in making an electrical connection with an electrical plug and cable assembly. One method commonly used to close such receptacle covers is to incorporate a Torsion spring as part of the hinging mechanism.
More particularly, certain electrical receptacle cover plates are provided with a means on the inner surface thereof for interlocking with the plug when the plug is inserted in the receptacle to secure the plug and cable assembly in the receptacle. One such receptacle features a protuberance extending from the inner surface of the cover such that when the plug is inserted into the receptacle the Torsional action of spring forming part of the cover plate hinge biases the inside surface of the cover plate against the plug such that the protuberance is disposed between the end of the plug and a raised surface on the plug such that it interlocks the plug and cable assembly with the cover plate and secures it to the receptacle as long as the Torsional biasing means of the cover plate remains intact or produces the force necessary to maintain such interlocking. Electrical receptacles with hinged cover plates having a protuberance on their inner surface for interlocking and securement of plug and electrical cable assemblies to the receptacle are, used, for example, to provide detachable electrical connections between Tractor-Trailer Vehicles. The receptacle is usually mounted on the front panel of the Trailer and the plug and cable assembly is electrically connected to the end of an electrical cable carrying current from the Tractor to the Trailer. Such installations particularly require attention to the condition of the cover plates ability to maintain the required force to interlock with the plug as hereinbefore mentioned since in many cases the weight of the electrical cable may create a force tending to pull the plug and cable assembly away from the receptacle; the torsional springs normally used to bias such cover plates against the plug may become weakened from use and/or corrosional effects; or vibrational forces may tend to disengage the connection. The use of coiled retractable electrical cables between Tractor-Trailer Vehicles has recently increased. Such coiled, retractile-type electrical cables, by design, result in an increased axial force tending to separate the plug from the receptacle then heretofore caused by the weight alone associated with non-retractile type electrical cables and thereby further increase the need of providing a means of securing the plug and electrical cable assembly against relative movement with the electrical receptacle. The novel clip of the present invention provides a low cost means of improving the means of securing a plug and electrical cable assembly in a receptacle having a hinged cover plate and in some cases extending the useful life of the cover plate.
Plug and receptacle assemblies of the type contemplated by this invention are known and are being used by the Trucking Industry. Examples of such assemblies are disclosed for example in U.S. Pat. Nos. 3,284,753, 3,887,256 and 3,915,476.
A device for securing a plug and electrical cable assembly in an electrical receptacle having a cover plate is disclosed, for example, in U.S. Pat. No. 2,158,385 in which a complex reaction arm and compression spring arrangement is used to bias the socket cover against the plug and to automatically disengage the plug from the socket when a Trailer is separated from its Tractor. The clip of the present invention comprises a simple, low cost means of improving securement of the type hereinbefore noted and does not require a great number of parts or an external compression spring to suitably provide such securement.
A one-piece clip addressed to similar subject matter is disclosed in U.S. Pat. application Ser. No. 668,263 filed Mar. 18, 1976, and assigned to the assignee of the present invention. Although suitable in certain applications, it has been found that the one-piece clip has dimensional limitations which preclude its use with a variety of electrical plug - receptacle assemblies in that it does not properly impinge upon the outer surface of the cover plate. The rotatable nature of the clip of the present invention and the integral means associated therewith of biasing the cover plate towards a closed position permit a more versatile use hereuntofore unknown to the art.